1. Field of the Invention
This invention relates to multi-component self-refrigerating-cascade refrigerators and, more specifically, to such refrigerators capable of operation in any or all orientations of the heat exchanger/phase separator section thereof.
2. Brief Description of the Prior Art
Prior art refrigeration systems have utilized multiple component refrigerants. In such prior art systems, the heavier liquid refrigerant phases were separated from the lighter vapor refrigerant phases by use of gravitational forces. Systems of this type operate properly only under a single orientation of the phase separator. This provides a serious disadvantage for those refrigeration systems wherein the final position of the heat exchanger/phase separator section is not known prior to the time of installation. Also, such prior art systems are incapable of operation in a zero gravity environment and liquid and vapor phase refrigerants can therefore not be properly separated under such conditions to achieve their designed operation goals. Prior art refrigeration systems and procedures also require a significant volume of liquid refrigerant at the entrance to the throttling devices. This is not a serious disadvantage for larger refrigerators, however it is important for miniature models. The extra liquid volume, particularly in the colder portions of the refrigerator, requires additional expansion or storage space to hold the high pressure (low boiling) components of the mixture as a superheated vapor at suitable limited pressures during shutdown.
The prior art systems are generally set forth in the patents of Podbielniak (U.S. Pat. No. 2,041,725), Fuderer (U.S. Pat. No. 3,203,194), and Missimer (U.S. Pat. No. 3,398,202). A typical publication describing the prior art is "One Flow Cascade Cycle", A. P. Kleemenko, 1959, International Institute of Refrigeration, Copenhagen, Denmark. In all instances, a liquid-vapor phase separator which uses gravity for operation is employed. The above are only exemplary of the prior art.